This project will provide the first comprehensive mechanistic and structural analysis of a mutarotase. The enzyme will be purified and characterized (metal ion and cofactor content, quaternary structure, etc.), then chemical, kinetic, and structure-function studies will be performed to investigate the catalytic mechanism. Chemical modification and/or affinity labeling experiments in addition to X-ray crystallographic studies undertaken by a collaborator will identify the active site and guide the selection of residues for analysis by site- directed mutagenesis. A long-term goal will be to compare this mechanism with those of other enzymes to gain further insight into mechanisms by which enzymes accelerate reactions. This project will enhance our understanding of carbohydrate metabolism because this enzyme plays a significant role in the utilization of galactose, and may be important in the transport of glucose across membranes. Therefore, this work has implications for the disease diabetes mellitus. Additionally, this project may assist cancer research, since some types of tumors exhibit an enhanced rate of glycolysis, and abnormalities in carbohydrate metabolism are seen in cancer patients with weight loss.